Patent document 1 discloses a general ball tap conventionally used which uses a method in which a valve orifice is opened and closed by a valving element via a lever type booster mechanism according to the swinging of a float that moves in response to water level changes, and a water level inside a water receiving tank is controlled by the balance between the buoyancy of the float and the water supply pressure.
In this ball tap, a strainer is incorporated on the primary side of the valve orifice, and by this strainer, foreign matter such as iron powder, sand, scale, and contaminants contained in water to be supplied are prevented from entering the secondary side of the valve orifice, and accordingly, the foreign matter is prevented from being caught between a valve seat provided around the secondary side of the valve orifice and a valving element provided in a manner enabling it to seat on and separate from the valve seat.
Foreign matter adheres to and deposits on the strainer during use, so that the strainer had to be periodically cleaned so as not to be clogged and cause an operation failure of the ball tap.